Braking apparatus for closure members

ABSTRACT

A braking apparatus has a main body for connection to one of a frame and a closure member mounted on the frame to undergo linear reciprocating movement between open and closed positions of the closure member. A tubular shaft is mounted in a main body for undergoing rotation. A resistance member is rotatably mounted on the tubular shaft and is disposed in an interior space of the main body containing a braking fluid. A spiral rod for connection to the other of the frame and the closure member is screw-threadably engaged with the tubular shaft so that the tubular shaft undergoes rotation when the spiral rod and the tubular shaft are relatively moved in an axial direction of the spiral rod. When the closure member undergoes linear reciprocating movement, the main body or spiral rod relatively moves in the axial direction of the spiral rod, the tubular shaft and the resistance member undergo rotational movement, and the resistance member receives a resistance of the braking fluid so that the tubular shaft rotates under a braking force of the braking fluid and reduces a movement speed of the closure member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to braking apparatuses for closure members and, more specifically, to a braking apparatus for braking movement of a closure member for a portal, such as a door or window opening.

2. Background Information

Self-closing apparatuses for automatically closing a door by use of a spring, a weight, a slope rail, etc., in a sliding door or a folding door, for example, are known. When such self-closing apparatuses are used, a braking apparatus is employed for the purpose of braking the movement of the door just before its closing position in order to moderate the impact effect with a door frame. While such braking apparatuses are structured so as to apply resistance against the movement of the door, they are associated with many problems. For example, a self-closing apparatus employing pneumatic pressure tends to easily lose service durability, whereas a hydraulic pump-type apparatus is associated with a large mechanical loss and its braking distance cannot be made long.

JP-A-2001-303843, JP-A-2002-121959, and JP-A-2002-54348 describe self-closing apparatuses of such a type that an apparatus main body is disposed at a right angle relative to the movement direction of a door, and a rotation shaft disposed on the main body is rotated via a rack gear and a pinion gear, by which braking is applied to the rotation of the rotation shaft. In these conventional self-closing apparatuses, it is necessary to arrange the rack gear and the pinion gear in mesh with each other so as to convert straight reciprocating motion of the door to rotational motion of the rotation shaft, and even if the rack gear and the pinion gear are slightly shifted, a loud irritating noise is generated upon engagement. In addition, the volume of the entire self-closing apparatus becomes large, and it sometimes cannot be disposed in a small space.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a a braking apparatus for braking movement of a closure member to moderate an impact effect when the closure member moves to a preselected position.

It is another object of the present invention to provide a braking apparatus for braking movement of a closure member and which is compact so that it can be installed in a small space.

It is still another object of the present invention to provide a braking apparatus for braking movement of a closure member and which has high durability, a simple structure, and is economical to manufacture.

It is yet another object of the present invention to provide a braking apparatus for braking movement of a closure member without the necessity of using a rack gear or a pinion gear.

The foregoing and other objects of the present invention are carried out by a braking apparatus for a closure member. The braking apparatus has a main body for connection to one of a frame and a closure member mounted on the frame to undergo linear reciprocating movement between open and closed positions of the closure member. The main body has an interior space containing a braking fluid. A hollow shaft is mounted in the main body for undergoing rotation. A resistance member is disposed in the interior space of the main body containing the braking fluid and is mounted on an outer periphery of the hollow shaft for rotation therewith. A spiral rod is configured for connection to the other of the frame and the closure member. The spiral rod is disposed in and screw threadably engaged with the hollow shaft so that the hollow shaft undergoes rotation when the spiral rod and the hollow shaft are relatively moved in an axial direction of the spiral rod.

When the closure member undergoes linear reciprocating movement between open and closed positions, the corresponding main body or spiral rod relatively moves in the axial direction of the spiral rod and the hollow shaft undergoes rotational movement together with the resistance member. Since the resistance member is disposed in the interior space of the main body containing the braking fluid, the rotational movement of the resistance member, and thus the hollow shaft, is retarded by the braking fluid, thereby braking a movement speed of the closure member.

Thus when the closure member moves as described above, the corresponding main body or the spiral rod relatively moves in the axial direction of the spiral rod, and since the spiral rod and the hollow shaft are screw threadably engaged, the linear reciprocating movement of the closure member is converted to rotational motion to thereby rotate the hollow shaft. Since the resistance member receives the resistance of, and is retarded by, the braking fluid, the hollow shaft rotates under a braking force of the braking fluid and reduces the movement speed of the closure member.

In one embodiment, the resistance member is fixed to the hollow shaft, thereby effecting braking in both directions when the closure member is opened and closed. Alternatively, the resistance member is mounted on the outer periphery of the hollow shaft via a one-way clutch so that the resistance member can be adjusted to rotate or not to rotate together with the hollow shaft depending on the rotational direction of the hollow shaft. When the hollow shaft rotates in such direction that the resistance member will be connected to the hollow shaft by the one-way clutch, it is possible to effect braking against the movement of the closure member.

Moreover, since the main body having the hollow shaft is positioned along the axial direction of the spiral rod, the volume of the entire braking apparatus can be made small and only a small area is required for installation of the braking apparatus.

In one embodiment, the a screw-threaded portion of the spiral rod is formed with an irregular pitch, thereby making it is possible to change the number of rotations of the hollow shaft under a braking force during rotation and to adjust the braking force. Alternatively, the screw-threaded portion of the spiral rod is formed by twisting a flat bar, thereby facilitating manufacture thereof. Furthermore, when a wire, a shaft, etc. are used as a self-closing apparatus for the closure member, if the spiral rod is formed in a hollow shape and the wire is inserted through the hollow portion, the braking apparatus can be installed without obstructing the structure of the self-closing apparatus.

In yet another embodiment, the braking apparatus includes biasing means disposed between the main body and the spiral rod for biasing the main body and the spiral rod to return to original positions before starting the relative movement. By this construction, the closure member can be automatically returned to a preselected position (e.g., a closed position).

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description of preferred embodiments of the invention, will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the invention, there is shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangement and instrumentalities shown. In the drawings:

FIG. 1 is a front view of a braking apparatus according to the present invention shown in a particular application to a closure in the form of a sliding door;

FIG. 2 is a side view of the braking apparatus and sliding door shown in FIG. 1;

FIG. 3 is a cross-sectional view showing an embodiment of a braking apparatus according to the present invention in which a resistance member is mounted on a hollow shaft via a one-way clutch;

FIG. 4 is a cross-sectional view showing another embodiment of a braking apparatus according to the present invention in which a resistance member is mounted on a hollow shaft without using a one-way clutch;

FIG. 5 is a partial front view showing an embodiment of a spiral rod for the braking apparatus according to the present invention;

FIG. 6 is a partial front view showing another embodiment of a spiral rod for the braking apparatus according to the present invention;

FIG. 7 is a cross-sectional view showing another embodiment of a braking apparatus according to the present invention;

FIG. 8 is an explanatory view showing another embodiment of the braking apparatus according to the present invention; and

FIG. 9 is an explanatory view showing yet another embodiment of the braking apparatus according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

While this invention is susceptible of embodiments in many different forms, this specification and the accompanying drawings disclose various forms as examples of the use of the invention. The invention is not intended to be limited to the embodiments so described, and the scope of the invention will be pointed out in the appended claims.

Referring now to the drawings in detail, wherein like numerals are used to indicate like elements throughout, there is shown in FIGS. 1-9 embodiments of a braking apparatus according to the present invention for braking movement of a closure member for a portal. The braking apparatus is particularly used, for example, to brake movement of a closure member just before its closing position in order to moderate the impact effect and to ensure the gentlest possible closing. As used herein, “portal” means an opening which is associated with a closure member for controlling the passage therethrough. For example, when the portal is an opening formed by a door or window frame, the closure member is a door or window, respectively, for controlling the passage (i.e., opening and closing) through the opening. The door may be in the form of a single pane door, a sliding door or a folding door which is used to control the passage into a structure (e.g., a house) or to control the passage between rooms within the structure. The braking apparatus of the present invention is also adapted for braking doors of pieces of furniture, such as drawers or flaps, to prevent these from reaching or hitting their end positions with force and irritating noise.

FIGS. 1-2 show a braking apparatus of the present invention used in connection with a sliding door 1 (hereinafter “door”). The door 1 is disposed within a door frame 4 having a vertical frame 2 and an upper rail 3 so that the door 1 is mounted for undergoing reciprocal movement between open and closed positions. The door 1 has a door roller 5 disposed at an upper portion thereof, opens and closes when the door roller 5 runs on a rail 6, and is urged in such a direction that it is closed by a self-closing apparatus not shown in the figures.

The braking apparatus has a main body 7 and a spiral rod 8 which is inserted through the main body 7. One of the main body 7 and the spiral rod 8 is installed or mounted on the door 1, and the other of the main body 7 and the spiral rod 8 is installed or mounted on the door frame 4 so that the main body 7 and spiral rod 8 undergo relative movement in the axial direction of the spiral rod 8 when the door 1 is opened or closed. In the embodiment shown in FIG. 1, the main body 7 is fixed to the upper rail 3 of the door frame 4 and the spiral rod 8 is non-rotatably fixed to a door roller bracket 9 of the door 1, and the spiral rod 8 is movable in the opening and closing direction of the door 1. The main body 7 is fixed to the upper rail 3 of the door frame via a mounting structure (not shown) which may be a structure integral with the main body 7 or other separate and independent structure for integrally connecting the main body 7 to the upper rail 3.

FIG. 3 is a partial cross-sectional view showing an embodiment of the braking apparatus according to the present invention. The main body 7 is formed in a substantially cylindrical shape and has a first end formed with a through-hole 10 and a second open end opposite the first end. An end cap 12 having a through-hole 11 extends into the open end of the main body 7 and is connected to the main body 7 to define an interior space 19 in the main body 7 for containing a braking fluid.

A tubular or hollow shaft 14 is mounted on the main body for undergoing rotation. The hollow shaft 14 has a flange 13 and shaft portions 14 a, 14 b extending from opposite sides of the flange 13 and terminating at respective first and second ends of the hollow shaft 14. The shaft portion 14 b extends through the through-hole 10 of the main body and the through-hole 11 of the end cap 12. A stopper pin 15 is mounted on an outer circumferential surface of the shaft portion 14 b near the second end of the hollow shaft 14 for preventing detachment of the hollow shaft 14 from the main body 7. A washer 17 is disposed between the stopper pin 15 and a step portion of the end cap 12. Sealing members 18 (e.g., O-rings) made of a suitable sealing material are disposed between the outer circumferential surface of the shaft portion 14 b and the main body 7 and the end cap 12 for providing a sealing function therebetween. The sealing members 18 are accommodated in respective grooves 7 a and 12 a formed in the main body 7 and the end cap 12.

A resistance member 20 is rotatably mounted on the outer circumferential surface of the shaft portion 14 b at a position within the space 19 of the main body 7 containing the braking fluid. The resistance member 20 is spaced by spacers 16 from the main body 7 and the end cap 12 in a longitudinal direction of the hollow shaft 14. In the embodiment shown in FIG. 3, the resistance member 20 is mounted on the shaft portion 14 b via a one-way clutch 21. The one-way clutch 21 limits the rotational movement of the resistance member 20 in one direction of rotation. Stated otherwise, the one-way clutch 21 controls the rotational movement of the resistance member 20 so that the resistance member 20 will either rotate or not rotate following the rotation of the hollow shaft 14 depending upon the rotational direction of the hollow shaft 14. The one-way clutch 21 is of the type, for example, having an inner ring (not shown), integrally connected to the shaft portion 14 b (i.e., the driving side) and an outer ring (not shown) integrally connected to the resistance member 20 (i.e., the driven side).

In operation, when the door 1 undergoes linear reciprocating movement between open and closed positions, the spiral rod 8, which is non-rotatably fixed to the door 1 via the bracket 9, relatively moves in the axial direction thereof. As a result of the axial movement of the spiral rod 8, and since the spiral rod 8 and the hollow shaft 14 are screw-threadably engaged, the hollow shaft 14 undergoes rotational movement together with the resistance member 20. Stated otherwise, the linear reciprocating movement of the door 1 is converted to rotational motion to thereby rotate the hollow shaft 14 and the resistance member 20. Since the resistance member 20 is disposed in the interior space of the main body 7 and immersed in the braking fluid, the resistance member 20 receives the resistance of or is retarded by the braking fluid, and the hollow shaft 14 rotates under a braking force and reduces the movement speed of the door 1. Thus the braking fluid constitutes means for retarding the rotational movement of the resistance member 20 and the hollow shaft 14 to thereby reduce the movement speed of the door 1.

In the embodiment shown in FIG. 3, the resistance member 20 and the one-way clutch 21 are separate and independent components. Alternatively, as discussed below with respect to the embodiment shown in FIG. 7, the resistance member 20 is omitted and the outer ring of the one-way clutch 21 is mounted on the outer circumferential surface of the shaft portion 14 b and used as the resistance. By this construction, the overall dimensions of the braking apparatus can be reduced.

FIG. 4 shows another embodiment of the braking apparatus according to the present invention. The braking apparatus shown in FIG. 4 is substantially the same as the braking apparatus shown in FIG. 3 except that the one-way clutch is omitted from the braking apparatus of FIG. 4. Instead, in the embodiment of FIG. 4 a resistance member 20 a is integrally connected directly to the outer circumferential surface of the shaft portion 14 b.

The threaded structures of the hollow shaft 14 and the spiral rod 8 and the manner of engagement therebetween will be described below with reference to the embodiments of the braking apparatus shown in FIGS. 3-7.

The hollow shaft 14 and the spiral rod 8 are screw-threadably engaged so that the hollow shaft 14 will rotate when the hollow shaft and the spiral rod are relatively moved in the axial direction. More specifically, a threaded portion formed on an outer periphery of the spiral rod 8 is a male screw or threaded portion 8 a having a large lead angle, and formed to have either a single screw thread or a multiple screw thread. A threaded portion formed on an inner surface of the hollow shaft 14 is a female screw or threaded portion 14 c for threaded engagement with the threaded portion 8 a of the spiral rod 8. The female threaded portion 14 c may be formed over substantially the entire length of the hollow shaft 14, as shown in FIG. 7, or partially provided in the axial direction as shown in FIGS. 3-4. Alternatively, projections shaped as female threaded portions may be formed at selected portions of the inner surface of the hollow shaft 14 and used as the female threaded portions.

In the embodiments described herein, the relative linear and and corresponding rotational movement between the spiral rod 8 and the hollow shaft 14 are accomplished by the spiral rod 8 being screw-threadably engaged with the hollow shaft 14. It is understood by those skilled in the art, however, that other forms of connecting means between the spiral rod 8 and the hollow shaft 14 are suitable so long as the spiral rod 8 and the hollow shaft 14 are relatively moved in an axial direction of the spiral rod 8 and the hollow shaft 14 and the resistance member 20 undergo rotational movement when the door 1 undergoes linear reciprocating movement between the open and closed positions.

Referring now to FIGS. 5-6, the male threaded portion 8 a of the spiral rod 8 is formed by twisting a narrow flat plate-like substrate. In this instance, as shown in FIG. 5, the threaded portion 8 a may be formed with a constant pitch so that a lead L will be equal over the entire length of the spiral rod 8. Alternatively, as shown in FIG. 6, the threaded portion 8 a may be formed with an irregular pitch by varying the pitch to, for example, (L), (L+a), (L+2a), . . . . If formed with an irregular pitch, it is possible to change the number of revolutions of the hollow shaft 14 in the middle of movement to change the braking force.

The spiral rod 8 is preferably formed to have such a length that corresponds to the movement distance of the door 1 so that the spiral rod 8 will always be in threaded engagement with the hollow shaft 14 when the door 1 is opened and closed. Alternatively, the spiral rod 8 may be formed to have such a length that at a portion of the spiral rod 8 at which braking is to be effected to the movement of the door 1, the spiral rod 8 is inserted into the hollow shaft 14 to start the threaded engagement. In the embodiment shown in FIG. 4 in which the one-way clutch is omitted and the resistance member 20 a is integrally connected to the outer circumferential surface of the shaft portion 14 b of the hollow shaft 14, when the spiral rod 8 is always in threaded engagement with the hollow shaft 14 when the door 1 is opened and closed, braking can be effected to the movement of the door 1 in both opening and closing directions of the door 1. Furthermore, in the embodiment shown in FIG. 3 in which the resistance member 20 is mounted on the hollow shaft 14 via the one-way clutch 21, braking can be effected to the movement of the door 1 when the door moves in such a direction that the rotation of the hollow shaft 14 is transmitted to the resistance member 20 by means of the one-way clutch. In this case, when the door 1 moves in a reverse direction, no load is applied to the movement of the door 1. Preferably, the braking force is effected to the movement of the door 1 when the door moves in a door-closing direction.

FIG. 7 shows another embodiment of the braking apparatus according to the present invention in which a braking force can be varied or adjusted. In this embodiment, an inner cylinder 23 is disposed in a main body 22 for undergoing movement in an axial direction of the main body 22, but prevented from undergoing rotation relative to the main body 22. An adjusting member 24 is mounted in the main body 22 for undergoing rotation. More specifically, the adjusting member 24 has a screw portion 24 a formed on an outer peripheral surface portion thereof for engagement with a screw portion 23 b formed in an inner peripheral surface portion of the inner cylinder 23. The adjusting member 24 has a small-diameter end portion 26 which protrudes outwardly from an end cap 27 integrally connected to the main body 22. When the screw portions 23 b, 24 a of the inner cylinder 23 and the adjusting member 24, respectively, are engaged, a space 25 is defined in the main body 22 for containing a braking fluid. The inner cylinder 23 has a projection 23 a formed on an outer peripheral surface and extending in an axial direction thereof. The projection 23 a engages a receiving groove 22 a formed in an inner surface of the main body 22 so that the inner cylinder 23 is permitted to move in the axial direction relative to the main body 22 but is prevented from undergoing rotation relative to the main body 22.

A hollow shaft 29 extends through a through-hole 30 formed in the main body 22 and a through-hole 31 formed in the adjusting member 24 and is mounted for undergoing rotation relative to the main body 22 and the adjusting member 24. A one-way clutch 28 is mounted on an outer circumferential surface portion of the hollow shaft 29 so that the one-way clutch 28 is disposed in the space 25 containing the braking fluid. As described above, the braking apparatus in this embodiment does not use a resistance member separate and independent from the one-way clutch 28. Instead, an outer ring (not shown) of the one-way clutch 28 which mounted directly on the outer circumferential surface portion of the hollow shaft 29 is used as the resistance member. A stopper pin 32 is mounted on an outer circumferential surface of the hollow shaft 29 for preventing detachment of the hollow shaft 29 from the main body 22.

A spiral rod 33 has a hollow portion 34 and a male screw or threaded portion 33 a formed on an outer circumferential surface thereof for threaded engagement with a female screw or threaded portion 29 a of the hollow shaft 29. The hollow portion 34 of the spiral rod 33 is configured to receive therethrough a wire 35 which communicates to a winding drum (not shown) of a self-closing apparatus (not shown).

By the foregoing construction, when the adjusting member 24 is rotated by rotating the end portion 26, the inner cylinder 23 moves in the axial direction and an area of the inner cylinder 23 facing the resistance member (i.e., the outer ring of the one-way clutch 28) is changed. As a result, the resistance effect of the braking fluid to rotation of the resistance member can be changed or adjusted to thereby vary the braking force to the hollow shaft 29. Thus the adjusting member 24 constitutes adjusting means for adjusting the braking force of the braking fluid.

FIG. 8 shows another embodiment of a braking apparatus according to the present invention. In this embodiment, the braking apparatus comprises urging or biasing means 38 encircling a threaded portion of a spiral rod 37 and disposed between a main body 36 and a support portion 37 a of the spiral rod 37 for biasing the main body 36 and the spiral rod 37 to preselected original positions thereof (e.g., original positions of the main body 36 and the spiral rod 37 at which the door is closed). Assuming that the spiral rod 37 is connected to the door and the main body 36 is connected to the door frame as described above for the embodiments of FIGS. 3-4, when the door is moved towards an opening direction, the main body 36 and the spiral rod 37 are relatively moved in the axial direction, and together with this movement, the biasing means 38 is pulled or compressed, by which a biasing force is accumulated in the biasing means 38. By this biasing force, when the door is released, the main body 36 and the spiral rod 37 are automatically returned to their original positions (i.e., the door is closed). Accordingly, in this embodiment, the door braking apparatus also functions as a closing apparatus of the door.

In the braking apparatus described above with reference to the embodiment of FIG. 3, for example, the spiral rod is mounted so that it does not rotate during operation of the braking apparatus. In this embodiment, when the main body and the spiral rod are relatively moved in the axial direction, the hollow shaft always rotates, and the rotation is transmitted to the resistance member via the one-way clutch.

FIG. 9 shows another embodiment of the braking apparatus according to the present invention in which the spiral rod is mounted for undergoing rotation. More specifically, a rod holder 39 is mounted on the door frame 4. A first end portion 40 a of a spiral rod 40 is supported by the rod holder 39 so that the spiral rod 40 is permitted to rotate and to move in an axial direction of the spiral rod 40. A stopper pin 41 is integrally connected to an outer circumferential surface of the spiral rod 40 for preventing detachment of the spiral rod 40 from the rod holder 39. A main body 42 is integrally connected to the door (not shown), and the spiral rod 40 is screw-threadably engaged with a hollow shaft 43 of the main body 42 as set forth above for the spiral rod 8 and the hollow shaft 14 in the embodiment of FIG. 3. The door frame has a mounting member or fixing portion 44 provided with a holding member 45 (hereinafter “clutch holder”) supporting a clutch 46. A second end portion 40 b of the spiral rod 40 is supported by the clutch holder 45. The clutch 46 controls rotation of the spiral rod 40 between a rotating state and a non-rotating state. The clutch 46 connects the spiral rod 40 to the fixing portion 44 so that the spiral rod 40 rotates when the door is moved towards one of an opening direction and a closing direction, and so that the spiral rod 40 does not rotate when the door is moved towards the other of the opening direction and the closing direction.

Various types of clutches may be selected for the clutch 46. For example, in the embodiment shown in FIG. 9 the clutch 46 comprises a dog clutch having clutch members 47 and 48 provided with respective engagement claws 47 a, 48 a on confronting surfaces thereof. The clutch member 47 (first clutch member) is integrally connected to the fixing portion 44 and the clutch member 48 (second clutch member) is integrally connected to the spiral rod 40 by a pin 49. The spiral rod 40 extends through a through-hole 50 of the clutch member 47 so that the spiral rod is capable of undergoing rotational and slidable movement relative to the clutch member 47. A stopper 51 is mounted with a pin 52 to an outer peripheral surface portion of the spiral rod 40 at the second end portion 40 b thereof for controlling or limiting movement of the spiral rod 40 in the axial direction (i.e., in the direction towards the rod holder 39).

Preferably, the clutch members 47 and 48 and the clutch holder 45 are made of a suitable plastic material, and the clutch member 47 is formed in one piece with the clutch holder 45. Alternatively, the clutch member 47 and the clutch holder 45 are fabricated as separate and independent members and then integrally connected to one another, such as by bonding. Furthermore, while in the embodiment of FIG. 9 the spiral rod 40 extends directly through a through-hole of the clutch holder 45 and the through-hole 50 of the clutch member 47, the spiral rod 40 may be mounted to the clutch holder 45 and the clutch member 47 for undergoing rotational and slidable movement relative thereto via a separate clutch shaft (not shown) extending through the through-holes of the clutch holder 45 and the clutch member 47.

By the foregoing construction of the braking apparatus, when the main body 42 moves towards the right in FIG. 9 (i.e., towards the rod holder 39) by the movement of the door, the spiral rod 40 also moves towards the right by being pulled by the hollow shaft 43, and the clutch member 48 is released from the clutch member 47, whereby the spiral rod 40 can freely rotate. Accordingly, the spiral rod 40 cannot rotate the hollow shaft 43 and the resistance member 53, and therefore does not effect braking to the movement of the door. This state of the braking apparatus is shown in FIG. 9.

From the state of the braking apparatus shown in FIG. 9, when the main body 42 moves to the left in FIG. 9 (i.e., toward the clutch holder 45) by the movement of the door, the spiral rod 40 also moves to the left by being pulled by the hollow shaft 43, and the clutch member 48 is engaged with the clutch member 47. As a result, the spiral rod 40 is kept in a non-fixed state. Accordingly, when the main body 42 is further moved towards the left direction in FIG. 9, as mentioned above, the hollow shaft 43 which is screw-threadably engaged with the spiral rod is rotated, and the resistance 53 disposed on the hollow shaft 43 receives the resistance of the braking fluid and rotates, thereby effecting the braking to the movement of the door.

In the foregoing embodiment shown in FIG. 9, the main body 42 is disposed on the door side and the spiral rod 40 is disposed on the door frame side. However, the substantially same function can be obtained when the main body 42 is disposed on the door frame side and the spiral rod 40 is disposed on the door side.

The foregoing embodiments of the braking apparatus according to the present invention have been described above with a particular application to a sliding door. However, it is understood by those skilled in the art that the braking apparatus of the present invention is also adapted for use with other types of closure members in the form of opening and closing mechanisms which undergo straight reciprocating motion, such as a folding door or a double-hung window. Additionally, the braking apparatus of the present invention is also adapted for braking doors of pieces of furniture, such as drawers or flaps, to prevent these from reaching or hitting their end positions with force and irritating noise.

Thus the foregoing described embodiments according to the present invention provide a braking apparatus for braking movement of a closure member to moderate an impact effect when the closure member moves to a preselected position (e.g., a closed position) either by manual movement or by a self-closing apparatus. The braking apparatus is compact so that it only requires a relatively small space for its installation, is highly durable, has a simple structure, and is economical to manufacture. Furthermore, the braking apparatus of the present invention can effectively brake movement of a closure member without the necessity of using a rack gear or a pinion gear.

From the foregoing description, it can be seen that the present invention comprises an improved braking apparatus for closure members. It will be appreciated by those skilled in the art that obvious changes can be made to the embodiments described in the foregoing description without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but is intended to cover all obvious modifications thereof which are within the scope and the spirit of the invention as defined by the appended claims. 

1. A braking apparatus for a closure member, the braking apparatus comprising: a main body for connection to one of a frame and a closure member mounted on the frame to undergo linear reciprocating movement between open and closed positions of the closure member, the main body having an interior space containing a braking fluid; a hollow shaft mounted in the main body for undergoing rotation; a resistance member disposed in the interior space of the main body containing the braking fluid and mounted on an outer periphery of the hollow shaft for rotation therewith; and a spiral rod for connection to the other of the frame and the closure member, the spiral rod being screw-threadably engaged with an inner surface of the hollow shaft so that the hollow shaft undergoes rotation when the spiral rod and the hollow shaft are relatively moved in an axial direction of the spiral rod; wherein when the closure member undergoes linear reciprocating movement between the open and closed positions, the main body or spiral rod relatively moves in the axial direction of the spiral rod, the hollow shaft undergoes rotational movement together with the resistance member, and the resistance member receives a resistance of the braking fluid so that the hollow shaft rotates under a braking force of the braking fluid and reduces a movement speed of the closure member.
 2. A braking apparatus according to claim 1; wherein the resistance member is mounted on the outer periphery of the hollow shaft via a one-way clutch.
 3. A braking apparatus according to claim 1; wherein the resistance member is integrally connected to the outer periphery of the hollow shaft.
 4. A braking apparatus according to claim 1; wherein the spiral rod has a screw-threaded portion formed on an outer surface of the spiral rod and having a constant pitch.
 5. A braking apparatus according to claim 4; wherein the screw-threaded portion of the spiral rod comprises a twisted flat bar.
 6. A braking apparatus according to claim 1; wherein the spiral rod has a screw-threaded portion formed on an outer surface of the spiral rod and having an irregular pitch.
 7. A braking apparatus according to claim 6; wherein the screw-threaded portion of the spiral rod comprises a twisted flat bar.
 8. A braking apparatus according to claim 1; wherein the spiral rod has a screw-threaded portion comprising a twisted flat bar.
 9. A braking apparatus according to claim 1; wherein the spiral rod has a hollow structure.
 10. A braking apparatus according to claim 1; wherein the main body comprises adjusting means for adjusting the braking force of the braking fluid.
 11. A braking apparatus according to claim 1; further comprising a biasing member disposed between the main body and the spiral rod for biasing the main body or the spiral rod towards a preselected position thereof.
 12. A braking apparatus according to claim 1; wherein the spiral rod is mounted for undergoing rotational movement; and further comprising a holding member for integral connection to the closure member or the frame, and a clutch disposed between the spiral rod and the holding member for controlling rotation of the spiral rod between a rotating state and a non-rotating state.
 13. A braking apparatus according to claim 12; wherein the clutch comprises a dog clutch having a first clutch member integrally connected to the holding member and a second clutch member integrally connected to the spiral rod for engagement with the first clutch member so that the spiral rod is placed in a non-rotating state.
 14. A braking apparatus according to claim 1; wherein the closure member comprises a door or a window and the frame comprises a door frame or a window frame, respectively.
 15. A braking apparatus for a closure member, the braking apparatus comprising: a main body for connection to one of a frame and a closure member mounted on the frame to undergo linear reciprocating movement between open and closed positions of the closure member; a tubular shaft mounted in the main body for undergoing rotation; a resistance member mounted on an outer periphery of the tubular shaft for rotation therewith; a spiral rod for connection to the other of the frame and the closure member; connecting means for connecting the spiral rod to the tubular shaft so that when the closure member undergoes linear reciprocating movement between the open and closed positions, the spiral rod and the tubular shaft are relatively moved in an axial direction of the spiral rod and the tubular shaft and the resistance member undergo rotational movement; and retarding means for retarding the rotational movement of the resistance member so that the hollow shaft rotates under a braking force and reduces the movement speed of the closure member.
 16. A braking apparatus according to claim 15; wherein the resistance member is mounted on the outer periphery of the hollow shaft via a one-way clutch.
 17. A braking apparatus according to claim 15; wherein the resistance member is integrally connected to the outer periphery of the hollow shaft.
 18. A braking apparatus according to claim 15; wherein the connecting means comprises a first screw-threaded portion of the spiral rod and a second screw-threaded portion of the tubular shaft threadably engaged with the first screw-threaded portion.
 19. A braking apparatus according to claim 18; wherein the screw-threaded portion of the spiral rod has a constant pitch.
 20. A braking apparatus according to claim 18; wherein the screw-threaded portion of the spiral rod has an irregular pitch.
 21. A braking apparatus according to claim 18; wherein the screw-threaded portion of the spiral rod comprises a twisted flat bar.
 22. A braking apparatus according to claim 15; wherein the resistance member is disposed in an interior space of the main body; and wherein the retarding means comprises a braking fluid disposed in the interior space of the main body. 